Photographic Glossary (Q to Z)
The meaning of the more common terms and phrases used in photography…
Rangefinder
A camera with a viewfinder that is separate from the lens. This is not an SLR.
Rear Focusing System
When focusing, only the rear lens group moves. This eliminates the physical length of the lens during focusing and allows for faster focusing. (see Internal Focusing.)
Reciprocity Failure
Photosensitive materials have a certain range of sensitivity. As the light level decreases out of this reciprocity range, the increase in duration required to produce an exposure becomes higher than the formula states (reciprocity law states that exposure = intensity × time); for instance, at half of the light required for a normal exposure, the duration must be more than doubled for the same result.
Recycling Time
The time it takes for a strobe or battery-pack to recharge enough that it can power a flash burst.
Reflected Light Reading
Light meter reading made by pointing the meter towards the subject. It will vary depending on the subject as different materials reflect different amounts of light.
Reflector
A tool for redirecting light - usually a white or metallic card or umbrella.
Reflex Camera
A camera that uses a mirror to reflect light onto ground glass for viewing and focusing.
Resolution
This is used to describe the size of the digital image the camera produces, and is usually expressed in terms of "megapixels" (how many million pixels). The number of pixels a camera captures is called the camera's resolution.
Retouching
To alter a finished print or piece of film in order to cover up undesirable marks or elements, such as scratches.
Reversal Materials
Photo-sensitive materials that when processed become positive images, i.e., slides, transparencies and certain print materials.
Roll-Film
Roll film is spool wound film protected from light by a paper backing, as opposed to 35mm film (and others) which is protected by a cartridge.
Roll-Film Adapter
An attachment for sheet film cameras that allows the use of roll film.
Rule Of Thirds
Composition rule which states that an image is divided into thirds both vertically and horizontally and that objects of interest be placed at the intersection these imaginary lines to ensure pleasing composition.
Safelight
A red or orange darkroom light that black and white photo papers aren't sensitive to.
Selenium Cell
A light sensitive electronic device that emits electricity in proportion to the amount of light falling on it. Used for light meters.
Separations
Black and white negatives that separate the continuous colours of an image into two to four colours for offset printing. The most common separations are for CMYK printing (cyan, magenta, yellow and black).
Sheet Film
Film that is supplied in sheets instead of rolls. A large and medium format that comes in sizes from 4x5 inches to 20x24 inches.
Shutter
The mechanical device in a camera that controls the amount of time light is allowed to expose the film.
Shutter Priority (TV Mode)
A camera exposure mode where the photographer chooses a shutter speed and the microprocessor in the camera sets a corresponding aperture for best exposure.
Silver Halide
The light sensitive component in chemically treated, photosensitive surfaces.
Single Servo AF
An autofocus mode that locks when the subject comes into focus and stays locked as long as the shutter release button is lightly pressed. Used when shooting stationary objects.
Single Lens Reflex Camera (SLR)
A camera that uses a mirror and prism to allow the photographer to see through the main lens.
Slave
A light sensitive trigger device used to synchronise strobes and flashes without an electronic synchronising cord.
Slide
A transparency (usually 35mm) mounted in a square paper or plastic frame.
Slide Film
Light-sensitive film that, when processed, produces a transparent film image. 35mm "transparencies" are usually mounted as slides. Transparencies can be printed or projected with a slide projector.
Soft Focus
An effect achieved by diffusing an image either in the camera or printing stage. Can be done with special lenses or by placing diffusion devices or materials between the light source and the light-sensitive material.
Solarization
Also known as the Sabbatier effect. This is usually achieved during the chemical process by exposing a developing image to white light. The effect is a partial reversal of the image.
Spectrum
The visible separation of light into coloured bands by directing white light through a prism.
Speed
In photography, this is the sensitivity of a photosensitive material and is expressed as either an ASA or ISO number.
Spherical Aberration
A lens fault which results in degraded image quality. It is caused by light rays passing through the lens from a single point on the optical axis and are focused at different points at the film or image sensor. Spherical aberration can be reduced by stopping (closing the aperture) down the lens.
Split Image Rangefinder
Two prisms with faces angled in opposite directions and used to aid in focusing. A subject will appear split while out-of-focus, allowing a photographer to adjust for accurate focus.
Spot Meter
A light meter, which takes its reading at an angle of 1 to 8 degrees. Used for the Zone System or to determine the reflective values of specific elements in a scene.
Spotting
Retouching dust spots or other fine blemishes in a photographic print with a small brush.
Standard Lens
This is the same as a “Prime Lens” or “Normal Lens”.
Stopping Down
To decrease the size of aperture in a lens, e.g., to stop down from f3.5 to f16. Increases depth-of-field and can reduce Spherical Aberration.
Teleconverter
An optical device used to increase the effective focal length of a lens. It is mounted between the camera and the lens and usually comes in two different sizes: 1.4X and 2.0X. A 1.4X teleconverter increases focal length by 1.4 times, while a 2.0X increases focal length by 2.0 times. The aperture of the lens is also increased by the same amount as the focal length is increased. For example, a 2.0X teleconverter increases focal length of a 200mm lens to 400mm; however, the aperture of F/2.8 is decreased to F/5.6.
Telephoto Lens
A lens with a long focal length - longer than the diagonal of the film format used. Usually 135mm or greater.
Tone
In photography, usually refers to the grey values in an image.
Transparency
A processed and stabilized positive film image, i.e., a slide is a transparency.
Tripod
A collapsible camera support with three legs.
TTL
Refers to flash or exposure metering which is read "through the lens" at the film plane.
Tungsten
A metal filament used in most light bulbs. Makes a reddish/yellow coloured light. There are special films and filters for correcting the colour cast of tungsten light.
UD Glass
A Canon designation for lenses designed to correct for chromatic aberration. See: Ultra Low Dispersion.
Ultra Low Dispersion
A type of glass used by Canon to make lens elements. "UD" glass corrects for chromatic aberration.
Under-Exposure
Allowing too little light to reach a photosensitive material, such as film or image sensor. Results in a "thin" or light image with negative material and a "dense" or dark image with reversal material.
USM
Canon designation for "Ultrasonic Motor". Canon's fastest autofocus lens technology.
UV Filter
Filter used to reduce the amount of ultraviolet light reaching film. Ultraviolet light can cause an image to appear hazy.
View Camera
A camera, usually large format that has a ground glass back for viewing the subject.
Viewfinder
An optical viewing device for framing and focusing an image in a camera.
Vignetting
When light is blocked at the edge of an image, which can be caused by a combination of a wide-angle lens and filters. Can be caused on purpose for effect.
Wide-Angle Lens
A lens with a focal length less than the diagonal of the film format it's being used for. For 35mm, usually wider than 50mm. For medium format, wider than 90mm.
Zone System
A system developed by Ansel Adams, Fred Archer, and Minor White to pre-visualize, optimize and control black and white film exposure as well as the print process.
Zoom Lens
A lens which has a variable focal length, e.g., 70-200mm.
Related Articles;
